Nano-silica optimizes C: N: P: K stoichiometry and nutrient accumulation in Dendrocalamus brandisii seedlings

Bamboo plays an important role in forest ecosystem conservation and carbon sequestration, but the effects of foliar nano-silica on nutrient accumulation and stoichiometric regulation in bamboo remain unclear. In this study, six foliar SiO₂ nanoparticle (SiO₂ NP) concentrations, 0, 100, 200, 300, 400, and 500 mg·L⁻¹, were applied to Dendrocalamus brandisii seedlings. Leaf SPAD values, SiO₂ content, C, N, P, and K concentrations, and related stoichiometric ratios were determined. Results showed that the 300 mg·L⁻¹ treatment (T3) produced the most favorable overall response, particularly enhancing leaf SPAD values, SiO₂, P, and K accumulation and maintaining relatively high N content, while altering multiple stoichiometric ratios among SiO₂, C, N, P, and K. Correlation and PCA analyses indicated that SPAD was closely associated with SiO₂, N, and P contents. In contrast, the highest concentration, 500 mg·L⁻¹, reduced SPAD values and nutrient accumulation, suggesting that excessive nano-silica application may negatively affect seedling performance. These findings indicate that moderate SiO₂ NP application may improve leaf nutrient status and C: N: P: K stoichiometric coordination in D. brandisii seedlings, providing a potential supplementary approach for improving bamboo seedling quality and supporting conservation-oriented bamboo plantation management.